Squirrels are highly adaptable, omnivorous rodents that rely on opportunistic foraging to sustain their high energy levels. Their diet is flexible, changing significantly based on the local environment, the specific squirrel species, and the time of year. While they eat a wide variety of foods, they exhibit clear preferences for items that provide maximum caloric and nutritional return. The primary goal of their feeding behavior is to secure energy and nutrients necessary for daily activity and preparation for periods of scarcity.
Primary Dietary Staples
The “favorite foods” of squirrels are those rich in fats and proteins, which are essential for survival, especially during preparation for winter. Nuts and seeds are the core staples of this diet, sought after for their high-calorie content that allows for efficient energy storage. Walnuts, pecans, hazelnuts, and almonds are particularly favored due to their substantial size and rich, fatty composition.
Acorns are perhaps the most important single food item in many North American squirrel diets, though preference varies by type. White oak acorns, which contain lower levels of bitter tannins, are often consumed immediately upon discovery. Conversely, red oak acorns, which have a higher tannin content, are frequently cached for later, as the burial process can allow some of the bitter compounds to leach out.
Seeds are also highly desirable, with sunflower and pumpkin seeds offering concentrated energy sources. Squirrels use strategic caching behavior to ensure a stored food supply for winter months. They have an impressive spatial memory and a keen sense of smell to locate hundreds of buried caches, even under snow or soil.
Seasonal and Supplemental Foods
When nuts and seeds are scarce, squirrels broaden their diet to include seasonal and supplemental foods. During spring and summer, their diet shifts to fresh plant matter, which provides necessary vitamins, minerals, and hydration. This includes tender tree buds, flowers, young leaves, and fruits like berries, apples, and cherries.
Fungi, such as mushrooms and truffles, are also consumed, providing a source of nitrogen and minerals even when other food sources are lean. In periods of extreme scarcity, squirrels may resort to gnawing on tree bark and conifer buds to sustain themselves.
Squirrels are opportunistic omnivores and supplement their plant-based diet with animal protein. Small animal matter, such as insects, insect larvae, bird eggs, and even small nestlings, provides a high-protein boost. This varied intake ensures a balanced nutritional profile, allowing them to adapt to changing food availability.
Foods to Avoid Feeding Squirrels
Providing squirrels with certain human foods can be harmful due to toxicity or poor nutritional value. Processed foods, such as bread, crackers, and breakfast cereals, offer little nutritional benefit and lead to malnourishment by providing empty calories. Sugary snacks, candy, and high-sodium items like salted nuts can cause severe dehydration and kidney stress.
Specific items are acutely toxic and should never be offered, including chocolate and caffeinated products, which contain theobromine that squirrels cannot metabolize effectively. Avocado pits and skin contain the fungicidal toxin persin, which is harmful to many animals. Furthermore, moldy nuts or corn can harbor highly toxic aflatoxins that cause liver damage.
Peanuts, while often given to squirrels, are technically legumes and offer a limited nutritional profile compared to true nuts. Feeding squirrels a diet high in junk food or toxic items interferes with their natural foraging behavior and can severely compromise their long-term health.